JPH065580A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To eliminate particles left after etching by performing the etching of an upper layer before completely removing a layer to be etched by etching. CONSTITUTION:The surface of an oxide film which is a layer 13 to be etched is etched in a first etching tank 1 to remove particles on the surface of the layer 13, particles 17 strongly adhering to the surface and particles 18 biting into the etched layer with the biting depth of not more than 200Angstrom . Next, a semiconductor device is cleaned with a shower of pure water in a first cleaning tank 2. Next, etching is continued up to a final etching tank and then the layer 13 of the remaining oxide film is completely removed and at the same time particles with a larger biting depth than 200Angstrom of particles biting into the layer 13 are removed. Consequently, the number of particles after etching is finished may be reduced down to not more than 1/30 as compared with the conventional method.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a semiconductor device, and more particularly to a method for manufacturing a semiconductor device using wet etching.

[0002]

2. Description of the Related Art As semiconductor devices become highly integrated and miniaturized,
It is becoming more and more important to reduce particles (dust) adhering to a wafer in a semiconductor device manufacturing process. Although the degree and opportunity of wafer contamination are generally decreasing due to the clean room atmosphere and the elimination of dust in manufacturing equipment, the wet etching process is still a problem because the contamination level of particles is still high. In order to reduce this contamination level, particles are removed by cleaning.

As shown in the sectional view of an example of the semiconductor device before the wet etching step of FIG. 5A, in the manufacture of a semiconductor manufacturing device using a compound semiconductor substrate 12 such as GaAs, the substrate 12 is to be etched. The layer 13 is completely removed by one wet etching, leaving the protrusions 16 with overhangs on both sides, and the visor as shown in the cross-sectional view of the example of the semiconductor device after the wet etching step of FIG. In the case of manufacturing a device structure having a lateral hole 15 of a circular shape, as shown in a sectional view of an example of the semiconductor device before the wet etching step contaminated by particles in FIG. When the particles 14 are adhered on the layer 13 and are etched in an etching bath, the particles 14 are removed after the etching as shown in FIG. As shown in cross-sectional view of an example of the semiconductor device after the Ikuru contaminated the wet etching process, may enter into the lateral hole 15 on the structure, the lateral hole 15
Protrusion 16 that is closed and has an overhang in a predetermined shape
However, there is a problem that causes deterioration of characteristics of semiconductor measures and malfunction.

Therefore, as shown in FIG. 4, a vertical cross-sectional view showing a cleaning tank and an etching tank of a conventional method for manufacturing a semiconductor device using wet etching in the order of steps, the substrate (wafer ) 12 to remove particles, and then the substrate (wafer) 12 is etched in the etching bath 11 to reduce the occurrence of defects due to particles. When the substrate is heavily contaminated, the cleaning in the water washing tank 10 was performed a plurality of times by replacing pure water or using a plurality of water washing tanks by cascade water washing.

A compound semiconductor substrate 12 such as GaAs
In general, the alkali-hydrogen peroxide mixed solution, which is effective in removing particles, cannot be used as the cleaning solution for the water washing tank 10. For this reason, in the water washing tank 10, ultrasonic cleaning, which is a cleaning method using physical force, a method of rubbing with a jet of pure water (jet scrub), and a method of rubbing with a brush (brush scrub) are used together to perform pure water cleaning. I was going.

[0006]

However, the particle 1
When 4 is strongly bonded to the surface of the layer to be etched 13 or when the particles 14 are biting into the layer to be etched 13, it takes a long time to wash the substrate (wafer) 12 in the washing tank 10 shown in FIG. Particles cannot be removed even after carefully washing multiple times. In this case, there is a possibility that the particles 14 having a large particle size cannot be removed and remain even after cleaning, which causes deterioration of device characteristics of the semiconductor device and malfunction.

Further, pure water cleaning in combination with the physical force (ultrasonic wave, jet scrub, brush scrub) conventionally used for removing particles on a wafer completely removes particles of submicron size. However, there is a problem that the deterioration of device characteristics cannot be completely prevented.

[0008]

An object of the present invention is to provide a method of manufacturing a semiconductor device which solves these problems.

In order to achieve the above object, in the method of manufacturing a semiconductor device of the present invention, in the wet etching step, the surface of the layer to be etched is etched and removed by a predetermined thickness in the first etching bath to remove the layer to be etched. After removing some of the particles that are strongly bound to the surface of the substrate and some of the particles that have eaten into the layer to be etched, the particles on the layer to be etched are removed through a cleaning bath, and etching is completed in the final etching bath. Is.
Further, in order to remove particles more completely, surface etching of an etching layer and washing with water are repeated in a large number of etching baths and washing baths, and etching is performed completely in the last etching bath.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings.

FIG. 1 is a longitudinal sectional view in order of manufacturing steps of an embodiment of a method for manufacturing a semiconductor device of the present invention, and FIG. 2 shows an etching tank and a cleaning tank used in an embodiment of the manufacturing method of the present invention. It is a longitudinal cross-sectional view arranged in order of process. In order to prevent particles detached from the semiconductor device (wafer) in the etching solution from reattaching to the wafer, both the first etching tank 1 and the final etching tank 3 are covered with a dust filter to prevent A circulating filtering device 4 for removing particles is provided.

In the semiconductor device of FIG. 1A, the layer to be etched 13 of the semiconductor substrate 12 is an oxide film, and the film thickness is 3000 angstrom. Dilute hydrofluoric acid (or buffered hydrofluoric acid) is contained as an etching solution in the first etching bath 1 and the final etching bath 3 in FIG.

First, the surface of the oxide film, which is the layer to be etched 13 of the semiconductor device shown in FIG. 1A, is etched by a depth of 200 Å in the first etching tank 1 and is then placed on the surface of the layer to be etched 13. The particles 17 that were strongly bonded to the surface of the layer to be etched 13 and the particles 18 that dig into the layer to be etched and have a depth of 200 angstroms or less are removed. Even particles with a depth greater than 200 angstroms may be separated from the layer to be etched depending on the degree of exposure). This step is an etching step in the sense that the layer to be etched 13 is etched to a predetermined depth, and is a cleaning step in the sense that the particles 17 and 18 are removed from the semiconductor device, and therefore has the functions of two steps. Can be said. The greatest feature of this step is that most of the particles, which are the majority of the particles, on the surface of the layer to be etched 13 and the particles 17 strongly bonded to the surface of the layer to be etched 13 can be removed. Large particles 14 that clog the lateral holes 15 in FIG. 6 cannot be put into the small lateral holes in FIG. 1B in the state where this step is completed, so they drift in the etching solution and are collected by the dust filter to be stored in the semiconductor device. The probability of reattachment is low. Even if there are particles clogged in the small lateral holes, the lateral holes will be expanded in the next etching step, so that they will not remain in the end. In other words, after this process, the only particles left on the substrate are those that are unstablely redeposited on the surface of the substrate, stuck in small lateral holes, or have a small depth of more than 200 angstroms. Since this is the first step, if a large number of particles are present in advance, even if most of them are removed, the number of remaining particles that remain unstablely adhere to the substrate surface is still large, and cleaning may be insufficient. ).

Next, the semiconductor device shown in FIG.
By washing with pure water in the washing tank 2 of
As shown in FIG. 1C, most of the particles attached on the semiconductor device (wafer) can be removed. As a result, particles that move with the semiconductor device in the final etching bath 3 can be significantly reduced. Large particles 14 that clog the horizontal holes 15 in FIG. 6 cannot be put into the small horizontal holes in FIG. 1C in the state where this step is completed, so they are washed and removed with pure water and still dig into the layer to be etched. Except for the large particles, almost no particles remain.

Next, as shown in FIG. 1D, the semiconductor device is etched in the final etching bath 3 shown in FIG. 2 to completely remove the etching target layer 13 of the remaining oxide film, and then to dig into the etching target layer. Particles with a depth of more than 200 angstroms that have penetrated inside of the existing particles are removed.

As a result, the number of particles after the etching as shown in FIG. 6B can be reduced to 1/30 or less as compared with the above-mentioned conventional method, and the deterioration and defect of the device characteristics can be largely eliminated. I was able to.

FIG. 3 is a vertical cross-sectional view showing an etching bath and a cleaning bath used in another embodiment of the manufacturing method of the present invention, arranged in the order of steps.

The upper layer (surface layer) of the etched tank 13 made of an oxide film is etched by 200 angstroms each in the first etching tank 5 and the second etching tank 7, and the remaining lower etched layer 13 is the third tank. Etching tank 9
It is configured to be completely removed by. Further, between the treatments in the respective etching baths, there is provided a washing treatment in which the washing baths 6 and 8 wash the pure water with a shower water.

According to the method shown in the embodiment, the particles that have penetrated into the layer to be etched and have a depth of more than 200 angstroms invaded are completely removed only by etching the surface layer in the first etching bath 1. Can not. Also, when the number of particles on the wafer is large, some of the particles once removed from the wafer in the first etching tank 1 and eluted in the etching solution may be reattached and brought into the final etching tank 3. There is.

Even in such a case, according to the method of the other embodiment, the surface layer is further etched in the second etching tank 7 to a depth of 200 angstroms, and the first etching tank 5 is not completely removed. The depth is about 200 ~
After the particles having a depth of 400 angstroms or the particles reattached from the etching solution are removed, the final etching bath 9 can be used for complete etching.

By further etching the surface layer in the second etching bath 7, the number of particles after etching removal shown in FIG.
It could be reduced to 5 or less.

As still another embodiment, the layers to be etched are etched and cleaned while gradually removing the layers to be etched by using the third, fourth and fifth etching tanks and the third, fourth and fifth cleaning tanks. Therefore, it is possible to provide a method of manufacturing a semiconductor device having wet etching with less influence of particles.

[0023]

As described above, according to the method of manufacturing a semiconductor device of the present invention, in the wet etching step, before the etching target layer is completely removed by etching,
The upper layer (surface layer) is etched to remove the particles that were strongly bonded to the surface of the layer to be etched, and the particles that have bitten into the layer to be etched have a depth of less than a predetermined depth. By removing the particles on the wafer, it is possible to reduce the number of particles left at the end of etching. The method for manufacturing a semiconductor device of the present invention can reduce the number of particles on the wafer after the etching layer is removed to several tens of minutes compared to the conventional pure water cleaning in which physical force is used together. Deterioration can be greatly reduced.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view in order of manufacturing steps of an embodiment of a method for manufacturing a semiconductor device of the present invention.

FIG. 2 is a vertical cross-sectional view showing an etching bath and a cleaning bath, which are used in one embodiment of the manufacturing method of the present invention, arranged in the order of steps.

FIG. 3 is a vertical cross-sectional view showing an etching bath and a cleaning bath used in another embodiment of the manufacturing method of the present invention arranged in the order of steps.

FIG. 4 is a vertical cross-sectional view showing a cleaning tank and an etching tank used in an example of a conventional method for manufacturing a semiconductor device using wet etching, arranged in the order of steps.

5A is a sectional view of an example of a semiconductor device before a wet etching step, and FIG. 5B is a sectional view of an example of a semiconductor device after a wet etching step.

FIG. 6A is a cross-sectional view of an example of a semiconductor device before a wet etching process contaminated with particles,
FIG. 6B is a cross-sectional view of an example of the semiconductor device after the wet etching step contaminated with particles.

[Explanation of symbols]

 1 1st etching tank 2 1st cleaning tank 3 Final etching tank 4 Circulation filtering apparatus 5 1st etching tank 6 1st cleaning tank 7 2nd etching tank 8 2nd cleaning tank 9 Final etching tank 10 Water washing Tank 11 Etching tank 12 Substrate 13 Layer to be etched 14, 17, 18 Particle 15 Horizontal hole 16 Protrusion

Claims (2)

[Claims] 1. A method of manufacturing a semiconductor device having a wet etching step, the step of etching and removing an upper surface of a layer to be etched of the semiconductor device to a predetermined first depth in a first etching bath, and the semiconductor device. And a step of completely etching the layer to be etched in a final etching tank, the method for manufacturing a semiconductor device. 2. Between the step of cleaning the semiconductor device in the first cleaning tank and the step of completely etching the layer to be etched in the final etching tank, the semiconductor device is further covered in the second etching tank. 2. The method according to claim 1, further comprising a step of removing the upper surface of the etching layer by etching to a predetermined second depth and a step of cleaning the semiconductor device in a second cleaning tank. Manufacturing method of semiconductor device.